Band gap engineering of CeO2 nanostructure using an electrochemically active biofilm for visible light applications

Sajid Ali Ansari, Mohammad Mansoob Khan, Mohd Omaish Ansari, Shafeer Kalathil, Jintae Lee, Moo Hwan Cho*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

179 Citations (Scopus)

Abstract

Narrowing the optical band gap of cerium oxide (CeO2) nanostructures is essential for visible light applications. This paper reports a green approach to enhance the visible light photocatalytic activity of pure CeO2 nanostructures (p-CeO2) through defect-induced band gap narrowing using an electrochemically active biofilm (EAB). X-ray diffraction, UV-visible diffuse reflectance/absorption spectroscopy, X-ray photoelectron spectroscopy, electron paramagnetic resonance spectroscopy, Raman spectroscopy, photoluminescence spectroscopy and high resolution transmission electron microscopy confirmed the defect-induced band gap narrowing of the CeO2 nanostructure (m-CeO2). The structural, optical, photocatalytic and photoelectrochemical properties also revealed the presence of structural defects caused by the reduction of Ce4+ to Ce 3+ as well as an increase in the number of oxygen vacancies. The as-modified CeO2 (m-CeO2) nanostructure exhibited substantially enhanced, visible light-driven photoactivity for the degradation of 4-nitrophenol (4-NP) and methylene blue (MB) compared to the p-CeO 2 nanostructure. The enhancement in visible light performance was attributed to defects (Ce3+ and oxygen vacancy), resulting in band gap narrowing and a high separation efficiency of photogenerated electron-hole pairs. Photoelectrochemical investigations also showed a significantly-enhanced separation efficiency of the photogenerated electron-hole charge carriers in the m-CeO2 nanostructure under visible light irradiation. The DC electrical conductivity of m-CeO2 showed higher electrical conductivity than p-CeO2 under ambient conditions. This study provides a new biogenic method for developing narrow band gap semiconductor nanostructures for efficient visible light driven photocatalysis and photoelectrode applications.

Original languageEnglish
Pages (from-to)16782-16791
Number of pages10
JournalRSC Advances
Volume4
Issue number32
DOIs
Publication statusPublished - 2014
Externally publishedYes

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